HTTPUnit and/or HTMLUnit tests

1. Add database test has been implemented using HTTP unit, which probably is better to this purposes.
   • AddDatabaseTest.readList() - reads database list and remembers it
   • AddDatabaseTest.addDatabase() - randomly generates database details and adds it to the system
   • AddDatabaseTest.check() - check whether database was really added

2. Trivial download test has been implemented using HTTP unit, which probably is better to this purposes.
   • TrivialDownloadTest.readNext() - reads next database from database backup list
   • TrivialDownloadTest.download() - starts downloading currently selected database

3. Authentication test has been implemented using HTTP unit, because it uses mainly http requests to deal with tested forms and actions. The invoked methods are:
   • AuthenticationTest.readConfig() - reads generic username and password from the config file, remembers it and sets active
   • AuthenticationTest.login() - logs in with active username and password
   • AuthenticationTest.changePassword() - changes password of the user to randomly generated one
   • AuthenticationTest.logout() - logs out from the system